<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            width: 500px;
            height: 500px;
            background: red;
            margin: auto;
            /* 边框的粗细 */
            border-width: 5px;
            /* 边框的样式  实线solid 虚线 dashed 点线dotted*/
            border-style: dotted;
            /* 边框的颜色 */
            border-color: blue;

        }

        p {
            width: 500px;
            height: 500px;
            background: red;
            /* 顺序：边框的粗细 边框样式 边框颜色 */
            border: 5px solid #000;
        }
    </style>
</head>

<body>
    <div></div>
    <p>

    </p>
</body>

</html>